adverb, adverb taking the 'to' particle, noun or participle which takes 'suru'
Describes a slim, slender, or delicate build, often with a positive or graceful nuance. Used for people, body parts, or objects. Can be used adverbially with と or as a する-verb.
彼女はほっそりとした指をしている。
She has slender fingers.
この花瓶はほっそりしていて美しい。
This vase is slim and beautiful.